Switch



.April 17, 1962v J. o. ROE-SER 3,030,465

SWITCH Filed Aug. 30, 1960 IN VEN TOR.

John 0. oeser United! States AParent O 3,030,465 SWITCH John 0. Roeser,Park Ridge, Ill.

Filed Aug. 30, 1960, Ser. No. 52,947 16 Claims. (Cl. 200-67) Thisinvention relates in general to switches, and more particularly relatesto a rugged, low travel, electrical switch, wherein the contacts areencapsulated in a hermetically sealed enclosure.

The exigencies of modern-day aircraft and spacecraft have demanded thedevelopment of extremely rugged and compact electrical switchingdevices. These switching devices must withstand extremes in vibrationand shock resistance, must be operable over a wide range of ambienttemperatures, and must provide the utmost in vreliability under theseextreme conditions. Therefore, it is a general object of this inventionto provide a small compact electrical switch of the hermetic type whichis exceedingly rugged and has extremely high vshock and vibrationresistance.

Another object of this invention is to provide a reliable electricalswitch device of the above type wherein the contact mechanism isencapsulated in a chamber which is evacuated, there `being a truehermetic type seal which has a leak-rate of under *6 cc. per second.

It is another object of this invention to provide an electrical switchhaving the above characteristics which requires only a very low travelof the actuator member to actuate the switch blade while stillmaintaining the desired characteristics of high vibration and shockresistance. Y

It is another object of this invention to provide a switch of the snapaction type, which has a large overcentering movement of the contactactuator assembly to get positive controlled vibration resistanceswitching` action.

It is another object of this invention to provide a switch of theaforestated type which has no dead-centering characteristics, ispositive in operation, is easy to assemble,

and is otherwise well ladapted for the purposes for which it wasdesigned. p

The novel features that are characteristic of the inven- 'tion are setforth with particularity in the appended claims. The invention itself,however, both as to its organization and its method of operation,together with additional objects and advantages thereof, may =best beunderstood by the following description of a specific 'embodiment whenread in connection with the ac- FIG. 5 is a partial sectional view takenalong line 5-5 'l FIG. 7 is a view of the flexible insulator means priorl to its assembly to the apparatus; and

FIG. 8 is an enlarged partial sectional view of the 'upper portion ofthe actuator assembly shown in FIG. 2.

As shown in the drawings, the switch device 10 essentially comprises avery rugged cast base 12 and -a cover 14 which defines an internalsealed chamber 16. The base is preferably made of steel and it hasbeenfound Aconvenient to cast the base by the so-called investmentcasting method so as to get `an extremely strong and rugged component.The cover 14 is preferably formed of steel and fits into a suitablegroove in the base 12 and is braised or soldered to the base to providea rugged leak-proof seal for chamber 16. An evacuation outlet tube 18 isfixed in a suitable bore in the base 12 to provide a means of evacuatingthe chamber after assembly and then pinching off the tube in the usualmanner to completely seal the chamber.

The base 12 is formed with a plurality of spaced `aligned transverseapertures which are adapted to receive terminal pins 26, 28 and 30. Eachpin is preferably made of an electrically conducting metal, and has anangularly offset -depending portion 26A, 28A and 30A respectively eachof which is drilled and tapped to receive suitable terminal screws inthe bores 26B, 28B, 30B. The terminal pin bores in the 'base 12 aresealed by a compression glass seal 26C, 28C, 30C respectively, said sealbeing exceedingly rugged in structure and serves to electricallyinsulate the respective terminal pins from the steel base. It will benoted that the base 12 is also formed with a pair of spaced cross Ibores32 which serve as mounting holes to mount the switch unit in positionfor its desired application.

The terminal pins 26, 28 and 30 may be respectively ydesignated as thenormally open and normally closed and common terminal pins. A movablecontact assembly 34 is mounted on the common terminal 30 for coactionwith the ixed terminals. More particularly, an elongated perforatemember 36 is iixedly attached to the terminal 30 at one end and ispreferably made of a thin springy metal. As best shown in FIG. 3, aportion of the member 36 is blanked out at 38 to define a central tongueportion 30 having a wide base portion and a relatively narrow free endportion. The `blanked out portions 38 of member 36 is formed in asomewhat U-shaped configuration, the amount removed at the base beingconsiderably thicker than the arms, and in addition to the tongueportion provides a pair of narrow curved arm portions 42 and 44 whichterminate in a pair of iingers 46 and 48 at the free end of member 36(the curve is only in side elevational view-see FIGS. 2 and 6). It is tobe noted that the blanked out U-shaped aperture 38 does not extendcompletely to the free end of member 36. The fingers 46-48 are furtherformed in a manner to provide V-shaped notches as best shown in FIGS. 4and 6, for pivotal receipt of the contact carrying member later to bedescribed. A shallow U-shaped aperture 50 formed in the free end ofmember 36 denes the upright finger portions 46-48 of the curved armportions 42 and 44, but it should be noted that a small portion of themetal intermediate, the base of the U-shaped aperture 50 and thefurthest extent of the blanked out portion 38 remains after the blankingout procedure, so that the two arms 42-44 and fingers 46-48 will alwaysoperate simultaneously. While there are two arms and fingers, they areactually integrally connected at both ends. The interconnection of thetwo arms and lingers provides vibrational stability, a very importantfeature in the instant switch.

As shown in FIG. 6, the member 36 has arm portions 52 and 54 which arerelatively straight adjacent to the common terminal pin 30, but arecanted or offset slightly upwardly from the horizontal from the point ofattachment of the member to pin 30. At the outer extent of straightportions of 52 and 54, the arms are respectively engaged at points 56 bythe operating means which will be later described. See the point markedX in FIG. 3.) The arms then are reversely offset downwardly and nearAthe end thereof are sharply reversely curvedi upwardly substantiallythicker stiffening or rigidifying member 5'8, which is integrally joinedthereto. As shown, member 58 extends substantially along the entirelength of the 'tongue portion, terminatingjust short of the free endthereof, and the function of member 58 is to stabilize the tongue toafford vibration resistance.

A U-shaped contact carrying movable blade member 6@ is mounted forpivotal coaction with member 36, the lfree arms 62 and 64 of said member66 being inserted fin the V-shaped notches in the fingers 46-418. Themovable contact 66 mounted on member 66 has a very slightly raisedcentral portion or nib 66a on each face thereof and is biased intoengagement with the lower iixed contact 74 by spring member 68. Thespring member 68 Iis mounted at one end thereof in an aperture 70 formedVnear the base of the U in member 6i) with'its other end being firmlyxed in aperture 72 on the free end of tongue member 40. The arms 62-64and the fingers 464478 are separated just sufficiently to receive thespring member 68 which passes therebetween, the spring `in addition toproviding the biasing force for the movable contact assembly serves tolocate the contact carrying member 66 relative to member 36. As will beapparent, the contact 66 is biased toward engagement with the loweriixed contact 74 and is movable to engagement with the upper iixedcontact 76. Each of the fixed contacts 7'2-74 is preferably made of asilver brass laminate, the silver portions being adapted to come incontact with the movable contact.

It should be noted that the movable Contact has 'a sliding or wipingaction on each actuation thereof by the operator means, and which islater described. When the pivot point of the arms 62-64, in the notcheson the fingers 46-48, passes through center, the movable contact 66slides to the left as viewed in FIG. 6, to provide the very desirablewiping contact action. Also the characteristics of the arrangement shownis such that the pivotal connection point of the iingers 46-48 and arms67;-64 are forced, by reaction force, to a considerable over-centerposition, which provides a very stable vibration resistance assembly.Stated another way, the arrangement of the pivot point in the midpointof the spring causes the lingers t6-48 to pass considerably over thedead-center point after the switch has actuated in either direction.This over travel of the pivot point is caused by the reaction force ofthe movable contact engaging the fixed contacts. It will also beapparent that there is no dead centering of the movable contact 66 sincethe movable contact is always biased by the spring 68.

Low travel operator means 7S, in the form of an actuator assembly isbest shown in FIGS. l and 2. The actuator assembly essentially comprisesan internal elongated lever means 80, a cross pin member 96 and anoutside lever 98. These three components present a generally U-shapedforce transmitting configuration, with the U being turned on its side,members S0 and 9S forming the two arms of the U, the free ends of thetwo arms of the U essentially being the points of application of forceand transmission of force to the contact assembly. The internal lever 8Gis formed with a notch at one end to form short stubby leg portionsS2-S4. The other end of the lever 80 is necked down at S6 and has aslight cant or olfset in horizontal view (see FIG. 2) from the majorplane of member 80. A bore 88 is formed in the end surface to mount Itheycross link cylindrical pin member 96 which is irmiy xed therein.

A pair of glass bead members 92-94 are fused to the metal and therebyattached to the short stubbing arms 82-84 of the inner lever means 80 independing relation. The glass beads serve the dual function of being aforce transmitting member and the providing of electrical insulationbetween the lever Si) and the member 36. The beads 92-94 impinge uponthe respective arm portions at points S6 as aforestated. As shown inFIG, 5, the

operator lever Sti is formed with a central aperture which serves as 'aweight reducing means for the lever;

Central cross pin member 96 is firmly xed to members 80 and 98, abellows means 110 being interposed between the upper lever 93 and thehousing to provide a exible seal. The lever 98 is mounted on the outsideof the bellows 110 and terminates in a pair of upstanding tabs 100 whichmount a miniature ball-bearing roller mechanism 102. An over-travelpreventing means for the actuating mechanism in the form of an elongatedmember 104, having depending tabs 106 and an adjustable screw 108prevents damage to the internal structure of the switch. The tabs 106bottom on the top of the casing prevent more than the selectivelyadjustable amount of travel desired for actuation. It will beappreciated that the outside lever member 98 is made of thinner gagematerial than member 104 and hence is somewhat exible such that a severeforce applied to member 162 at the end of thejlev'er will cause member95S to flex but will not cause further actuation of the interior lever80.

The bellows 110 as aforementioned provides a -exible yseal for theoperator means and further tends to dampen any vibrations thatthesomewhat elongated lever means might normally be subject to when theentire switch 10 is in turn subjected to shock or to severe vibrations.More particularly, the bellows 110 is sealed to the upper portion fofthe housing at 112 and is fixed to the lever member 98 at 114. Theinterior of the bellows is preferably potted with a silicone rubbercompound 116. More particularly, the silicone rubber compound iscompounded by using a silicone rubber polymer which has a rather pasty,dry consistency, much like window putty. Into this material, by the useof rotating cylinders, is inserted a socalled blowing agent which is adry powdery chemical which sublimes on the application of slight heat toproduce a gas. Just a few percent of blowing agent is used, and the drypasty material is packed into the bellows cavity with a small spatulaand then the whole assembly is put into the oven at a temperature ofabout 250 F. The heating causes the blowing agent to sublime and therebyprovide small gas pockets within the silicone rubber compound. The neteffect is to force the silicone into the crevices of the bellows, forintimate contact therewith except for the areas wherein the compressedair is greater than the force of the gas generated by the sublimingmaterial. The silicone rubber occupies most all of the crevices andprovides a Vgood vibrational dampening effect. When the utmost invibrational resistance is desired for the switch, an additional pad ofthis silicone rubber compound is foamed in place (at 128) beneath theiiexible arm portions of member 36 to provide additional vibrationaldampening characteristics. However, the additional pad of material 128is not found to be necessary for vibration resistance when the switch issubjected to forces under 50 gravities with 0 to 2,000 cycles per secondvibration, the actuator being within .005 inch of the trip point, sincethe described switch structure without such additional material 12.8serves to provide that function.

As can be best seen in FIG. 2, a flexible supplementary insulator means118 (shown in its preassembled form in FIG. 7) is bent into a U-shapedform and is interposed, at the upper portion thereof, between the lever3i), and the fixed contact and the movable contact assembly. The member118 at one end is provided with a truncated corner 120 so as not tocover up the evacuation tube 18. Bores 124 and 126 in member 118respectively receive the terminal pins 26 and 23 during the assemblyoperation and the end of member 118 is reduced at its other end at 122so as to not interfere with the depending glass bead members 92 and 94when nally assembled.

From the foregoing description it will be apparent that a low travel,rugged, hermetically sealed switch is provided which is extremelyvibration resistant and adapted for applications requiring a high degreeof shock. The

switch has been found to operate very well over wide range of ambienttemperatures and tests have indicated that it will have a long,trouble-free field life.

Having thus described a single embodiment of the low travel, rugged,hermetically sealed switch, it is to be understood that the illustratedform was selected to facilitate the disclosure of the invention ratherthan to limit the number of forms the invention may assume. Variousmodifications, adaptations and alterations may be applied to thespecific form shown to meet the requirements of practice, without in anymanner departing from the spirit or scope of the present invention, andall such modifications, adaptations and alterations are contemplated andmay come Within the scope of the appended claims.

What is claimed as the invention is:

l. A hermetic switch comprising housing means defining a sealed chamberhaving first, second, and third electrical terminal means sealinglyextending therethrough, first and second fixed contact means mounted onsaid first and second terminal means within said chamber,

lmovable contact means having a first position and movable to a secondposition relative to said first and second fixed contact means andcomprising a U-shaped relatively.

said elongated member and to bias the movable Contact.

against said first fixed contact means, and operator means sealinglyextendingv through said housing means and engageable with said flexibleportions of said elongated member and operable to move said free end tocause movement of said movable Contact from said first to saidy secondfixed terminal means.

2. A hermetic switch comprising housing means defining a sealed chamberhaving first, second and third electrical terminal means sealinglyextending therethrough, first and second fixed contact means mounted onsaid first and second terminal means within said chamber, movablecontact means having a first position and movable to a second positionrelative to said first and second fixed contact means and comprising arelatively rigid member carrying the movable contact, a second memberhaving a relatively flexible portion and a relatively rigid portion,fixed at one end to said third terminal means and having a free endspaced therefrom, said free end being configured for pivotal engagementof said contact carrying member, spring means engageable with saidcontact carrying member at one end and with said relatively rigidportion of said second member at the other end to maintain the pivotalconnection therebetween and to bias the movable contact against one ofsaidfirst and second fixed contact means, and operator means sealinglyextending through said housing means and engageable with said flexibleportion of said second member and operable to move said free end thereofto cause movement of said movable contact from its said first to itssaid second position.

3. A switch comprising metalic housing means defining a chamber havingfirst, second, and third electrical terminal means electricallyinsulatingly extending therethrough, first and second terminal meanswithin said chamber, movable contact means having a first position andmovable to a second position relative to said first and second fixedcontact means and comprising a movable relatively rigid member carryinga movable contact, a second member having a relatively flexible portionand a relatively rigid portion, fixed at one end to said third terminalmeans and having a free end spaced therefrom, said free end beingconfigured for pivotal engagement 6 with said contact carrying member,spring means engageable with said contact carrying member at one end andwith said relatively rigid portion of said second member at the otherend to maintain the pivotal connection therebetween and to bias themovable contact against said first fixed contact means, operator meansincluding a metallic actuator means extending through said housing meansand engageable with said flexible portion of said second member andoperable to move said free end thereof to cause movement of said movablecontact from said first to said second fixed terminal means, saidoperator means including first insulation means operably interposedbetween said actuator means and said flexible portion of said secondmember and flexible second insulation means interposed between saidactuator means and said second fixed contact means, said contactcarrying member and said spring means. p

4. The switch set forth in claim l wherein the operator means comprisesa generally U-shaped member and flexiblebellows on said housingjmeans,one arm of the U- .shaped member being disposed outside of the housingmeans for engagement on the free end thereof and the other armbeingdisposed within the sealed chamber for engagement with the movablecontact means adjacent the free end thereof, the flexible bellowsengaging the 'bail portion of the U-shaped member which extendstherethrough to thereby mount the operator means on said housing meansso that the free ends inside and outside the housing means are insubstantial alignment with each other.

5. The switch set forth in claim 4 wherein the bellows is substantiallyfilled with flexible plastic foamed material to increase the vibrationalresistance thereof.

6. The switch set forth in claim l wherein first, second and thirdterminal means extend through a single wall of said housing means torespectively mount said first and second fixed contacts means and saidmovable contact means.

7. The switch set forth in claim 1 wherein the elongated perforatemember is of relatively thin spring material having a short tongueportion blanked out of the central portion thereof to define a pair ofspaced flexible arm portions, said flexible arm portions each having afirst portion extending below the major plane of said perforate memberand a second portion extending above said major plane.

8. The switch set forth in claim 7 wherein said second portion of eachof said arms are formed into a finger having a V-shaped configurationgenerally normal to the major plane of said perforate member at the freeend thereof to provide coacting pivotal surfaces for said contactcarrying member.

9. The switch set forth in claim 8 wherein said tongue portion isrigidified to provide a support for a portion of said biasing means notsubject to vibration.

10. The switch set forth in claim 9 wherein said contact carrying memberis bifurcated to form spaced legs having end portions coacting with saidV-shaped configurations of said fingers, the biasing means being in theform of a coiled spring confined between the leg portions of saidcontact carrying member and extending between the fingers at the freeends of said perforate member for attachment to the end of saidrigidified tongue member.

11. A hermetic switch comprising housing means defining a sealed chamberhaving first, second, and third electrical terminal means sealinglyextending therethrough, first and second fixed contact means mounted onsaid first and second terminal means within said chamber, movablecontact means having a first position and movable to a second positionrelative to said first and second fixed contact means and comprising aU-shaped relatively rigid contact carrying member, an elongatedperforate member having relatively flexible portions and a relativelyrigid portion fixed at one end to said third terminal means and having afree end spaced therefrom,

said free end being configured for pivotal action with said Contactcarrying member, biasing means engaging said contact carrying member atone end and said relatively rigid portion of said elongated member atthe other end to maintain the pivotal connection between said U-shapedmember and said elongated member, to provide positive snap action overcentering and to bias the movable contact against said first fixedcontact means, and operator means sealingly extending through saidhousing means and engageable with said flexible portions of saidelongated member and operable to move said free end to cause movement ofsaid movable contact from said first to said second fixed terminalmeans, said biasing means and said U-sahped member upon engagement ofsaid movable contact with said first and second fixed terminal meanscausing said free end to move by reaction force to a stable vibrationresistant over center position.

12. A hermetic switch comprising housing means defining a sealed chamberhaving first, second and third electrical terminal means sealinglyextending therethrough, first and secondfixed contact means mounted onsaid first and second terminal means within said chamber, movablecontact means having a first position and movable to a second positionrelative to said first and second xed contact means and comprising a LJ-shaped relatively rigid contact carrying member, an e'longated perforatemember having relatively fiexible portions and a relatively rigidportion fixed at one end to said third terminal means and having a freeend spaced therefrom, said free end being configured for pivotalengagement of said U-shaped member, spring means fixed to said U- shapedmember at one end and to said relatively rigid portion of said elongatedmember at the other end to maintain the pivotal connection between saidU-shaped member and said elongated member and to bias the movablecontact against said first fixed contact means, and operator meanssealingly extending through said housing means and engageable with saidflexible portions of said elongated mem-ber and operable to move saidfree end to cause movement of said movable contact from said first tosaid second xed terminal means, said operator means comprising anelongated lever means mounted for movement within said chamber andhaving an at-rest position in engagement with said housing means toprovide strong vibration resistance thereto.

13. The switch set forth in claim 12 wherein said operator means furtherincludes iiexible bellows means sealingly mounting said elongated levermeans, said spring means through said U-shaped member and flexibleportion of said elongated perforate member biasing said lever meanstoward engagement with said housing means.

14. The switch set forth in claim 13 wherein said operator means furtherincludes second lever means exterior of said housing means associatedwith the lever means interiorly of said housing means said second levermeans including adjustable over travel permitting means.

15. A switch comprising a generally rectilinear housing means having arelatively greater length than depth or height defining a chamber havingfirst, second, and third electrical terminal means extendingtherethrough, said third terminal being spaced by mounted adjacent oneend of said chamber, first and second fixed contact means mounted o nsaid first and second terminal means within said chamber and adjacentthe other end thereof, movable contact means having a first position andmovable to a second position relative to said first and second fixedcontact means and comprising a U-shaped relatively rigid contactcarrying member, an elongated perforate member having relativelyflexible arm portions and a relatively rigid central tongue portionfixed at one end to said third terminal means, said arms being connectedat a free end spaced from said fixed end for movement in the areaintermediate the ends of said chamber, said free end being configuredfor pivtol engagement of said U-shaped member, spring means fixed tosaid U-shaped member at one end and to said relativelyk rigid centraltongue portion of said elongated member at the other end to maintain thepivotal connection between said U-shaped member and said elongatedmember and to bias the movable contact against said first fixed contactmeans, and operator means extending through said housing means andengageable with said flexible arm portions of said elongated member andoperable to move said `free end to cause movement of said movablecontact from said first to said second fixed terminal means.

16. A hermetic switch comprising housing means defining a sealed chamberhaving first, second, and third electrical terminal means sealinglyextending therethrough, first and second fixedk contact means mounted onsaid first and second terminal means within said chamber, movablecontact means having a first position and movable to a second positionrelative to said first and second fixed contact means and comprising arelatively -rigid member carrying the movable contact, a second memberhaving relatively flexible spaced arm portions and a relatively rigidtongue portion fixed at one end to said third terminal means, saidsecond member having a free endy spaced` from said fixed end, said freeend being characterized as presenting substantially short spaced fingersdisposed at substantially right angles to said arm portions said fingersbeing connected together at the base thereof to define a U-shaped notch,said fingers being configured for pivotal engagement of said contactcarrying member, spring means engageable with said contact carryingmember at one end and with said relatively rigid tongue portion of saidsecond member at the other end, said spring means extending through saidU-shaped notch to maintain the pivotal connection between said rigidmember and second member and to bias the movable contact against one ofsaid first and second fixed contact means, and operator means sealinglyextending through said housing means and engageable with said flexiblearm portions of said second member and operable to move said free endthereof to cause movement of said movable contact from its said first toits said second position.

References Cited in the file of this patent UNITED STATES PATENTS2,415,546 Willman Feb. 1l, 1947 2,483,685 Willman Oct. 4, 1949 2,505,605Coake Apr. 25,

2,794,889 Bachman June 4, 1957 FOREIGN PATENTS 514,386 Italy Feb. 9,1955 540,179 Canada Apr. 30, 1957

